remulang / hmf

implementation of HMF type system, for higher rank types

HMF

HMF for higher rank polymorphisms.

Use python repl.py to experiment with the interactive type inference.

The Problem of HRT By HMF

However, I finally think this might not be what I want, the annotation is verbose and weak.

The reason why: I have to write this:

check HMF> let f = fun (g: some a. forall b. b -> a -> a) -> fun (b: forall b.b) -> fun a -> g b a
in f
forall a0. (forall a1. (a1 -> (a0 -> a0)) -> (forall a2. a2 -> (a0 -> a0)))

Instead of only specifying annotation in top level:

check HMF> let f: forall a. (forall b. b -> a -> a) -> forall b. b -> a -> a = fun g -> fun a -> fun b -> g b a in f
> Exception: cannot unify types forall a0. (a0 -> (gen<a1 -> gen<a1)) (^a2 -> (^a3 -> ^a4))

hmf's Issues

propagate may work and makes HMF appealing once again?

https://github.com/tomprimozic/type-systems/blob/master/first_class_polymorphism/propagate.ml